This paper represents the very basic work of bio-climatic classification of north-east India into warm and humid, cool and humid and cold and cloudy zones. This classification is extremely useful to the building-design for wide range of objectives such as climate responsive building design, building energy conservation, thermal comfort, out door design conditions, etc. This classification is based on the meteorological data collected over a period of more than 30 years, from Regional Meteorological Centre, Guwahati, India from 30 stations spread all over the region. Psychometric charts are prepared for each bio-climatic zone to assess the potential of solar passive design strategies for residential buildings. (C) 2007 Elsevier B.V. All rights reserved.